NEMS meets Bio-sensing; There´re plenty of things to do in the middle

We propose a new fabrication method for nanofluidic device with novel shapes using thermal shadow evaporation and wet anisotropic etching in aqueous KOH solution. The shadow evaporation of metal onto the sidewalls of topographic features, followed by the selective etching of the substrate, generates narrow channel structures with nanometer scales. And the wet anisotropic etching of silicon substrate in KOH solution provides the well-defined fluidic channels with triangular cross-sections as well as chamber structures with micrometer scales. We also demonstrate that a single DNA molecule could be driven in the nanofluidic device by electrophoresis, in which the linear stretching and electrophoretic migration of a DNA polymer molecule could be observed at a single molecule level. Finally, we investigate length-dependent mobility of chromosome-sized DNA in nanofluidic channel and successfully separate different lengths of DNA under simultaneous action of electric field as well as pressure gradient.